The present invention relates to absorbent articles. More particularly, the present invention relates to absorbent articles which include an absorbent structure formed from a liquid-bearing precursor material and configured with desired structural properties. The absorbent product can incorporate a wet-formed absorbent structure which exhibits desired levels of softness and flexibility when the absorbent structure is dry and when the absorbent structure is wet.
The performance objectives of disposable absorbent articles, such as infant diapers, include leakage prevention, dry feel to the wearer, and a comfortable fit throughout the product life. Accordingly, absorbent articles have typically contained an absorbent core to provide liquid handling and other absorbent functionalities required to meet the product performance objectives. The absorbent core of a conventional absorbent article has typically been composed of absorbent fibers, and a superabsorbent material has typically been combined with the absorbent fibers to increase the liquid absorbent capacity. The absorbent core has been formed in a substantially rectangular shape. The absorbent core has also been formed in an hourglass shape, a T-shape, or similar configuration with a reduced absorbent width in the central crotch region for improved fit and comfort.
Conventional absorbent cores have incorporated dry-formed materials which have been produced with various conventional airlaying techniques. The airlaying techniques have typically laid an air-directed mixture of absorbent fibers and superabsorbent to form a web of the Absorbent material.
When dry, the conventional dry-formed absorbent structures have been soft and conformable, but have had low strength. In addition, the dry-formed structures have had low integrity after they have been wetted.
As a result, additional components, such as supplemental carrier tissues or supplemental high-strength fibers have been employed to provide sufficient strength to the dry-formed absorbent materials and to provide-increased wet integrity. The added dry strength can, for example, allow the dry-formed materials to be more readily passed through conventional manufacturing processes, and the wet integrity can help the absorbent material maintain its shape and structure after the material has absorbed liquid.
Conventional absorbent cores have also incorporated wet-formed materials which have been produced with various wet-laying techniques. The wet-laying techniques have typically formed an absorbent web produced from a precursor material composed of a mixture of fibers and superabsorbent particles combined with water or other aqueous liquid. A particular wet-laying technique has processed the precursor material into a foam, and the foam has then been employed to form the desired web of absorbent material.
The absorbent structures produced from wet-formed absorbent materials have had greater strength and greater integrity. In particular, the wet-formed absorbent structures have exhibited greater strength and greater integrity after the absorbent materials have absorbed liquid. The wet-formed absorbent materials, however, have also had excessive stiffness and rigidity, particularly when the absorbent materials have been provided at the basis weights and amounts needed to provide desired levels of total absorbent capacity.
Consequently, there remains a need for absorbent structures which can provide desired combinations of strength, softness, flexibility, wet integrity and absorbent capacity.
Generally stated, the present invention provides an absorbent article having a longitudinal direction, and a lateral, cross direction. The article includes a liquid permeable top sheet layer, a substantially liquid impermeable backsheet layer, and an absorbent structure sandwiched between the top sheet and backsheet layers. The absorbent structure can include a wet-formed mixture of fibers and superabsorbent material, and can have selected properties, such as a selected edge-wise compression value, and a selected modified circular bend value. In particular aspects, the retention portion can include cellulosic fibers.
The present invention provides a distinctive absorbent structure formed from a liquid-containing precursor material which includes a mixture of fibers and superabsorbent particles. The absorbent structure exhibits desirable physical properties, such as softness, flexibility and conformance in both its dry and wet states. When wet, the absorbent structure can advantageously resist separating, bunching and clumping. Since the absorbent structure can better retain its integrity when wet, it can resist becoming mushy and sagging, particularly in the crotch region of the product. As a result, the absorbent structures and articles of the invention can provide increased strength, improved fit, reduced leakage, and reduced clumping, bunching or sagging during use.